In the design of many buildings which are to rely on solar energy for space heating in the winter time, especially passive solar heating systems, large areas of glass are provided on the southern exposure of the building. These large areas of glass allow large solar gain during the winter time, the light passing through the glass and heating objects within the building.
While passive solar heating systems as described above can be very effective during the winter, in many parts of the country they are extremely disadvantageous during summer months. In many areas, cooling loads in the summer are almost as large as heating loads in the winter, and attempts to properly shade the large souther exposure (or northern exposure in the southern hemisphere) windows utilizing overhangs and the like are not entirely effective. If reflective glass is used, the incident light is reflected onto surrounding buildings and objects providing undesirable heat gain therefor in the summer.
According to the present invention, there is provided a method and means for obtaining a large solar gain through a window assembly during the winter time, when such gain is desired, while at the same time effectively minimizing solar gain through the window assembly in warm weather. Thus, appropriate heating needs can be met in the winter time utilizing large window areas, while the window areas do not excessively increase cooling loads in the summer, and without experiencing the disadvantages associated with reflective glass.
According to one aspect in the present invention, a method and apparatus are provided for obtaining large winter gain through a window assembly of a building in cold weather, while minimizing solar gain through the window assembly in the warm weather. The window assembly includes first and second spaced transparent sheets defining a volume therebetween, and defining an exterior surface of the building with exterior air on the opposite side of the first sheet as the second sheet, and with the building interior air on the opposite side of the second sheet as the first sheet. Only in warm weather, when solar gain is not desired, exterior light incident upon the window assembly is caused to be reflected toward the building exterior and prevented from substantially passing into the building interior; and air is circulated from the building exterior between the transparent sheets and exhausted, after circulation, to the exterior of the building. Only in cold weather, when solar gain is desired, the exterior light incident upon the window assembly is allowed to pass through the transparent sheets into the building, and air may be circulated from the building interior between the sheets and exhausted, after circulation, into the interior of the building. A light reflecting device for effecting the selective reflection or passage of incident solar radiation preferably comprises a selective light reflecting device--such as a horizontal slat venetian blind assembly or a rolled sheet with portions of differing transparency--disposed between the first and second transparent sheets. When this device reflects incident radiation, the interior or exterior air is circulated between the reflecting device and the first transparent sheet before being exhausted.
According to another aspect of the present invention, a closure assembly in general is provided for a building exterior surface. The closure includes a first frame member with a first transparent solid sheet supported by the first frame member, and a second frame member with a second transparent solid sheet supported by the second frame member. Means are provided for spacing the first and second frame members and corresponding transparent sheets so that the sheets are substantially parallel and define an open volume therebetween. Light reflecting means, mounted in the open volume, are provided for selectively allowing the passage of light from the first transparent sheet to the second sheet, or preventing the passage of light from the first sheet to the second sheet (reflecting the light back toward the first transparent sheet). First vent means are provided for selectively allowing or preventing passage of air from exteriorily of the first frame member to a volume between the reflecting means and the first frame member, and second vent means are provided for allowing passage of air from within the volume between the reflecting means and the first frame member to a remote area. Further, third vent means are preferably provided for selectively allowing or preventing passage of air from exteriorily of the second frame member to a volume between the reflecting means and the first frame member, and fourth vent means for allowing the passage of air within the volume between the reflecting means and the first frame member to a remote area.
The second and fourth vent means may comprise a common conduit leading from the open volume; first and second branch conduits; and valve means for directing air flow in the common conduit to either the first or second branch conduits. The first and third vent means are preferably disposed in bottom portions of the first and second frame members, respectively, while the second and fourth vent means open into the open volume adjacent to the top portions of the first and second frame members. An exhaust fan may be disposed in the first branch conduit, which can lead from a common conduit to an area outside of the first sheet as the second sheet, and the second branch conduit can open into a building interior adjacent a ceiling fan which evenly distributes the circulated air.
The entire assembly, including vents, valves, reflecting means, etc., can be motorized and automatically controlled, and/or manual control means may be provided on the opposite side of the second sheet as the first sheet for effecting control.
It is the primary object of the present invention to provide an apparatus and method for obtaining large solar gain through a transparent closure assembly in cold weather, while minimizing solar gain through the closure assembly in warm weather. This and other objects of the invention will become clear from inspection and the detailed description of the invention, and from the appended claims.